Abstract
In the early visual cortex, neurons sensitive to different visual features tend to be spatially organized at fine scales, such as ocular dominance columns and orientation pinwheels in V1. In high-level visual category-selective regions in the ventral pathway, neurons are found to be sensitive to different visual features such as object parts, but whether there is generally fine-scale spatial organization of these neurons within each region remains unclear. Here we used high-field 7T fMRI to examine the spatial organization of neural tuning to different face parts within each face-selective region. Five kinds of face parts (i.e., eyes, nose, mouth, hair, and chin) were presented to participants while they were scanned in the MRI. In the right pFFA, contrasting the neural responses to eyes and mouth revealed consistent spatial patterns in all six participants. Aligned with the orientation of mid-fusiform sulcus, the posterior part of right pFFA was biased to eyes, while the anterior part was biased to mouth stimuli. Similar spatial tuning patterns were observed in the right OFA, but no obvious spatial pattern was found in the right aFFA, left OFA, or left FFA. Among other face parts, chin generated similar (but less robust) spatial response patterns as mouth, while no clear spatial pattern was observed in responses to nose and hair stimuli. Our results demonstrate that within some face processing regions, there exist systematic spatial organizations of neural tuning to different face parts. Such fine-scale spatial patterns may reflect the distribution of neurons sensitive to different dimensions in face feature space.
Acknowledgement: CAS Pioneer Hundred Talents Program, NSFC grant (No. 31322025), NSFC grant (No. 31540078)